exposed -- we're doing some crazy things with our kids now where we almost want to keep them in a sterile environment, not necessarily the best thing because that is how kids build up immunities, right? >> right. i mean now we are pretty much saying well, maybe it is good to eat a little dirt. >> okay. are you an actual doctor? where did we get this guest? okay. >> mankind survived for many generations doing so and it is only in the last few generations that we've become so clean. >> that's right. >> and i'm interested in the shellfish allergies because my mom had the same problem. she turned like 50. one day, she had crab and never again. >> you develop it late in life. once you developed it, it is there. >> and why would that develop all of a sudden? ican't really tell you that. >> is this anything can you do to -- other than be exposed as a young child. is there anything you can do to prevent allergies? >> i think maybe the answer is that you are constantly he can forked to things so that you keep your level of tolerance up. if you are allergic to an antibiotic, if you have been desensitized to it